Sound producer



arch 1 1924;; mswm L. .DE FOREST SOUND PRODUCER Filed Aug. 20, 1918 2 Sheets-Sheet 1 SOUND PRODUCER Filed Aug. 20. 1918 2 Sheets-Sheet 2 Patented ar. 18,1924.

LEE DE FOREST. OF NEW YORK. N. Y.. ASSIGNOR. BY MESNE ASSIGNILENTS, T O DE FOREST PHONOFILM CORPORATION, OF JERSEY CITY, NEW JERSEY, A CORPORA- HUN OF DELAWARE.

Application filed August 20, 1918.

To all whom it may concern:

Be it known that I. Luv. nu Fonnsr. a citizen of the l nited Qtatcs. residing at New York. county and State of New York,

have made av new and useful invention in Sound Producers. of which the following is a specification.

This invention relates to novel and eflicient means for producing sound.

The object of the invention is to produce means for producing sound which will eliminate the necessity of the use of dia phragms such as are employed in transmission of sound.

A further object of the invention is to provide means for producing a true undistorted sound.

Further objects of the invention will appear more fully hereinafter. 1

The invention consists substantially in the construction, combination. location. and relative arrangement of parts. all as will be more fully hereinafter set forth, as shown by the accompanying drawings and finally pointed out in the appended claims. 7

Referring to the drawings:

Fig. l is a view in elevation, largely diagrammatic, of a second producer constructed in accordance with my invention.

Fig. 2 is a sectional view taken on the line 2, 2, Fig. 1, looking in the direction of the arrows.

Fig. 3 is an enlarged detail sectionfshowing diagrammatically the arrangement of wires employed in accordance with my invention.

Fig. 4 is a transverse sectional view of a. slightly modified construction employed in accordance with my invention.

Fig. 5 is a longitudinal sectional view of the same.

Fig. 6 is a longitudinal sectional view of a still further modified construction embodying my invention.

Fig. 7 is a diagrammatic View showing the manner of use of the sound producer constructed in accordance with my invention.

Fig. 8 is a view partially in section in side elevation of a still further modified construction embodying my invention.

Fig. 9 is a similar view of a further modified construction embodying my invention.

Fig. 10 is a view in side elevation, partially sectional, of a modified structure emon bodying my invention.

SOUND PRODUCER.

Serial N0. 250,718.

Fig. 11 is a sectional view taken on the line 11, 11. Fig. 10, and looking in the direction of the arrows.

The same part is designated by the same reference character wherever the same occurs throughout the several views.

It is an established scientific fact that the expansion and contraction of a body emits sound waves. which, if the body be of a non-metallic substance. will he more'nearly free from distortion than is observed when metallic diaphragms are used. It is among the. special purposes of my present invention to secure the expansion and contraction of a body of non-metallic character to produce undistorted sound waves and to control the expansion and contraction of said body in any suitable manner, for example. by an electric current flowing through wires positioned suitably relative to the expansible body and suppliedfwith current from a suitable current source for the production of the sound.

My invention is based upon well establishcd principles of electricity, but due to the fact that the apparatus constructed in accordance with my invention necessarily employs line wires in great length, it has been necessary, to make a disclosure on the drawings which is capable of ready interpretation when taken in connection with the following description, to distort the showing of such apparatus principally in regard to the proportion of the parts shown, and I therefore wish it to be understood that such disproportionate disclosure is made with full knowledge that. it is disproportionate and merely as an aid to the description and understandin of the invention obtained therefrom. fn accordance with my invention I employ a pneumatic ball or sphere, or

other shaped body adapted to be supplied with suitable fluid, such for example, as air, through the valve 2, Fig. 1, the construction of which is immaterial, and consequently diagrammatically illustrated as an ordinary pneumatic tire valve, which valve is secured to the neck of the ball, sphere or other shaped body 1 to render the same airtight. If desired, and as shown, the portion of the body 1 opposite to the valve 2 may be slightly extended for a purpose which will be apparent later in the description. The inflat able body 1 is wound meridionally with a fine copper insulated wire between the valve end of the inflatable body 1 and the projecting end 3 so that each wire extending around the body 1 is of opposite polarity to the next adjacent wire on the body as diagrammatically illustrated in Fig. 3. The wires may be of single depth or in layers according to the size of the sphere, size of the wire, the strength of the tone desired to be produced, and the material of the wire. The wires lying side by side being of opposite polarity tend to repel each other when current is flowing therethrough thereby causing a slight expansion of the wires relative to the inflated body 1, the pressure within which causes the body to expand. The minute the current ceases flowing through the wires, the wires tend to assume their normal position causing the inflated body 1 to contract to its normal position.

In Figs. 4 and 5 I show a slightl modified construction wherein a small meta body, for example, an iron or steel core indicated at 5 is supported in a suspended position within the in atable body 1. This core is preferably in the form of a permanent magnet, with the south pole indicated at 6 and the north pole indicated at 7. The effect of the permanent magnet within the rubber ball or inflatable body 1 is to strengthen the magnetic force of the wire in causing the expansion and contraction of the rubber sphere 1. due to the controlling current in the wire as will be apparent.

In Fig. 6 I show a still further modified construction embodying the principles of my invention wherein the wire 8 from the source is grounded to the valve stem 2, which valve stem 2 carries the mush-room magnet bod 6' with the core 7 thereof of relatively sma 1 diameter. The other terminal 9 of the wire is led through the tube 2 and is wound around the core 7 of the magnet 6'. On the outer surface of the rubber sphere are cemented a large number of short fine iron wires formingi the armature for this magnet as shown in ig. 6. It will be noted that these wires are confined practically entirely to the equatorial space of the magnetic field. The effect of the current passing through the wire 8 is to cause an equatorial contraction of the rubber s here 1, which again assumes its normal position due to its natural elasticity and resiliency as soon as the current ceases to flow through the wire 8, 9.

In Fig. 8 I show a somewhat similar con struction but wherein the wire is wound eguatorially or laterally around the exterior o the rubber or inflatable container 1 in the form of a spiral coil, the leads of the wire in this instance are illustrated as being connected to one coil of a transformer 13, the other coil of which is connected to a suitable source of current 14 and the sound source, which, for the purpose of illustration, may be a microphone indicated, at l5. In this form of construction when current flows through the wire there is a contractive effect similar to the contraction of a coiled helix included in circuit with a current source.

This effect is enhanced by the magnetic action on the iron spheie (or permanent steel magnet) enclosed within the bulb. When the current supply is cut off or reduced, the bulb resumes its normal expanded condition, due to the expansive action of the air compressed within the same.

In Fig. 9 the construction is similar except that the wire instead of being wound equatorially or laterally is wound meridionally or vertically with adjacent wires of like polarity. This effects contraction of the bulb or container upon the completion of the circuit through the wire.

In Fig. 10 the inflatable body indicated generally at 20 is in the form of a cylinder to which is secured a plurality of iron wires or strips 21 in any suitable manner, for

example, cemented, or vulcanized to the exterior surface thereof and extending longitudinally the cylindrical portion thereof. These iron strips 21 are slightly separated from each other and are in the form of laminations. The cylinder is surrounded by a magnet 23 likewise in cylindrical form with inwardly turning flanges 24, which flanges constitute the respective poles ofthe magnet. Wound on the inside of the magnet 23 is the iron' wire 25 in the form of a coil. An annular space indicated at 26 is left between the magnet poles and the coil and the periphery of the inflatable cylinder 20 to allow ample egress of sound waves set up in the air in this space due to the vibration. of the cylindricalbag. Air or other fluid is admitted to the bag through either of the necks thereof as will be apparent. When current is caused to flow through the coil 25 an attraction is created between the magnetic cylinder 23 and the laminations 21 secured to the exterior peripheral surface of the bag 20, thereby causing an expansion of the same. As the current through the wire 25 is varied the vibrations thus secured by the expansion and contraction of the bag create corresponding sound waves. In Fig. 7 I show one manner of utilizing the construction of my invention wherein the vibrating sphere is diagrammatically illus' trated at 50, as located at the focus of the parabolic horn 51 so that the sound waves from the device 50 are radiated from the parabolic horn in a concentrated unidirectional manner well known in the art. Many further modified forms and constructions may readily occur to those skilled in the art without departing from the spirit and scope of my invention, and I have therefore not attempted to show or describe the many different constructions capable of operatin in the manner hmetcfwre described pro'uce foregoing description to be interpreted in an illustrative sense rather than a limiting sense. With sounders constructed in accordance with my invention it is possible to obtain true sounds free from distortion due to mechanical movements as it is apparent that the basic source of sound is from a fluid such as air set in vibration electrically and in effect cushioned on air to eliminate any possible distortion arising through vibrations set up mechanically or by any vibrating member held in metallic contact at any portion thereof.

Having now set forth the objects and nature of my invention, and having shown am. described various embodiments thereof, what I claim as. new and useful and of my own invention and desire to secure by Letters Patent is 1. The combination with an elastic air filled container, of electric wires,and means for expanding and contracting said container in accordance with the current ,flowing through said wires.

2. The combination with an elastic air filledcontainer, a metallic core suspended in said container, and electric, wires wound around the exterior of said container.

3. The combination with a hollow rubber container sealed with air therein, of a metal body suspended in said container, of means cooperating with said metal body for caus ing said container to expand and contract.

'4. The combination with a hollow rubber container sealed with air therein, of a metal body suspended in said container, of wires wound around said container.

5. The combination with a hollow rubber container sealed with air therein, of a metal body suspended in said container, of electrically controlled means cooperating with said metal body for causing said container to expand and contract.

6. Means for generating sound waves comprising a sealed inflated elastic body, 4

wires wound around the exterior surface of said body, and means for controlling the current through said wires by and in accordance with the sound to be produced to thereby expand and contract said body as and for the purpose described.

7. Means for nerating sound waves comprising a sea ed inflated elastic body, Wires wound laterally around the exterior surface of said body, and means for controlling the current through said wires by and in accordance with the sound to be produced to thereby expand and contract said body as and for the purpose described.

In testimony whereof'I have hereunto set my hand on this 8th day of August A. 1D.

LEE DE FOREST. 

